Endocrine Flashcards
pituitary apoplexy-what is it, presentations, and treatment
acute hemorrhage into the pituitary gland
- associated with preexisting pituitary adenoma
- severe headache, cranial nerve involvement (bitemporal hemianopsia, ophthalmoplegia), meningeal irritation
- treat with glucocorticoid replacement (prevent life-threatening hypotention) or surgical decompression
Kallmann syndrome-what is it
absence of GnRH secretory neuronsin the hypothalamus due to defective migration form the olfactory placoid
-associated with mutatio nin the KAL-1 gene or fibroblast growth factor receptor-1gene
–> central hypogonadism and anosmia, delayed puberty
mutation in what gene is associated with medullary thyroid cancer
RET proto-oncogene
what are the 3 P’s of MEN1
parathyroid adenomas, pituitary tumors, and pancreatic endocrine tumors
how can patients still metabolize fructose when fructokinase is deficient
hexokinase takes over fructose metabolism
what can and can’t use ketones for energy
can: brain, kidneys, cardiac muslce and skeletal muscle
can’t: erythrocytes b/c lack mitochondria
ketones produced int eh liver
how can ethanol cause hypoglycemia
by inhibiting gluconeogensis
clinical manifestations of congenital hypothyroidism
normal at birth
-lethargy, enlarged fontanelle, protruding tongue, umbilical hernia, poor feeding, constipation, dry skin, jaundice
-6 P’s: pot-bellied, pale, puffy-faced, protruding umbilicus, protuberant tongue, poor brain development
growth hormone stimulate release of insulin-like growth factor-1 (IGF-1) from what organ?
liver
how come you don’t see high urinary excretion of ketones with type 2 diabetes
high total insulin levels suppress ketone formation
mechanism of beta-blockers for thyrotoxicosis (thyroid storm)
decreases peripheral conversion of T4 to T3 by inhibiting iodothyronine deiodinase
presentation of urea cycle disorders
vomiting, tachypnea, and confusion/coma secondary to hyperammonemia
most common disorder: ornithine transcarbamylase deficiency–> elevated urinary orotic acid
avidin in egg whites binds to ______
biotin (vitamin B6)–> deficiency in biotin leads to dermatitis, alopecia, changes in mental status, myalgias, anorexia, and lactic acidosis
essential amino acid in phenylketonuria
Tyrosine–> cannot be synthesized from phenylalnine due to deficiency of phenylalanine hydroxylase so can’t convert phenylalanine to tyrosine
most common complication of statin
myopathy
how can glucocorticoids lead to hyperglycemia
increase hepatic gluconeogenesis and glycogenesis along with peripheral antagonism of insulin
mechanism of action of Finasteride
5-alpha-reductase inhibitor that suppresses periperal conversion of testosterone to dihydrotestosterone
used for treatment of benign prostatic hyperplasia and androgenetic alopecia (increased in 5-alpha-reductase is associated with androgenetic alopecia)
3 primary effects of PTH
- increase osteoclastic bone resorption–> increase calcium and phosphate release into the circulation
- increase renal calcium reabsorption and reduces phosphate reabsorption (excrete phosphate but keep calcium)
- increased formation of active vitamin D, which increases intestinal calcium and phosphate absorptioin
what is neurophysin
carrier protein for oxytocin and vasopressin (ADH), hormones produced within the paraventricular and supraoptic nuclei, respectively, and released from the posterior pituitary
-point mutation in neurophysin II lead to hereditary hypothalamic diabetes insipidus
how can estrogen increase total T4
estrogen raises circulating thyroxine-binding globulin –> reduce free T4 and free T3
–> increase in thyroid hormone production
side effect of niacin
-decrease renal excretion of uric acid leads to acute gouty arthritis, flushing, hyperglycemia, and hepatotoxicity
use to decrease hepatic synthesis of triglycerides and VLDL and reduces clearance of HDL
mechanism of action for meglitinides
short-acting glucose-lowering medication
close ATP-dependent K+channel in the pancreatic beta cell membrane, inducing depolarization and stimulating insulin release
mechanism of action for SGLT2 inhibitors
oral anti-diabetic
- decrease proximal tubular reabsorption of glucose to promote urinary glucose loss
- should be avoided in those with moderate-to-severe renal impairment
side effect of thioamides (propylthiouracil, methimazole)
skin rash, agranulocytosis (rare), aplastic anemia, hepatotoxicity
methimazole=teratogen
2 signs of hypocalcemia
associated with hypoparathyroidism
Chvostek sign: facial muscle contraction elicited by tapping on the facial nerve anterior to the ear
trousseau sign: carpopedal spasm triggered by prolonged inflation of a blood pressure cuff around arm
what organelle is found in all steroid-producing cells (eg, cells in the adrenals, gonads, and liver)
smooth ER
mechanism of actions of sulfonylureas (eg, glyburide)
increase insulin secretion rate of residual pancreatic islet beta-cells and reduce blood glucose levels in patients with type 2 diabetes mellitus
–> increase circulating C-peptide
mechanism action of Leuprolide
GnRH analog to suppress testosterone levels in treatment of prostate cancer
pulsatile fashion–> agonist properties
continuous fashion–> downregulation of GnRH receptors on gonadotropin cells in the pituitary gland
what is Hartnup disease
autosomal recessive metabolic disorder due to inactivating mutations affecting the neutral amino acid transporter (esp. tryptophan), in small intestine and proximal tubule of kidney
–> need tryptophan to get niacin so patient has niacin deficiency
which glucose transport proteins (GLUTs) is the only one that is responsive to insulin?
GLUT4 (skeletal muscle cells and adipocytes)
the other ones are insulin-independent
complications of familial chylomicronemia syndrome?
recurrent episodes of acute pancreatitis, lipemia retinalis (milky-appearing retinal vasculature), and eruptive xanthomas
syndrome- auto recessive with lipoprotein lipase (LPL) deficiency so can’t clear dietary lipid loads (esp. chylomicrons)
how does the calcium levels regulate the secretion of parathyroid hormone (PTH)
through calcium-sensing receptors= transmembrane G-protein-coupled (metabotropic) receptors that help to regulate the secretion of parathyroid hormone (PTH) in response to changes in circulating calcium levels
histological finding of medullary thyroid cancer
nests or sheets of polygonal or spindle-shaped cells with extracellular amyloid deposits derived from calcitonin
alpha-2 adrenergic receptors _____ insulin secretion, and beta-2 adrenergic receptors ________ insulin secretion
inhibit; stimulate
what are the acute effects of corticosteroids on the white blood cell count
increased neutrophil count (“demargination” of neutrophils previously attached to vessel wall)
decreased lymphocyte, monocyte, basophil, and eosinophil counts
characteristic of Klinefelter syndrome
primary hypogonadism (elevated FSH and LH, low testosterone); long lower extremities; small, firm testes; and azoospermia
methimazole vs. propylthiouracil (PTU)
both are antithyroid drugs used to decrease thyroid hormone production
methimazole preferred due to hepatotoxicity of PTU
methimazole is teratogenic so PTU is preferred in the first trimester of pregnancy
complications of subclinical hyperthyroidism
hypertension, accelerated bone resorption, and atrial fibrillation
can also be caused by medications like levothyroxine
prolactin production is stimulated by
TRH
in patients with primary hypothyroidism, the increased production of TRH by the hypothalamus can lead to hyperprolactinemia
